Current mortar mixing apparatus do not function properly in cold weather. The mixing process typically involves combining an aggregate and a binder with water in such a fashion that the desired mixing ratio is obtained.
In extremely cold weather the aggregate, for example sand, may freeze due to the significant moisture content in the sand. The water used in the mixing process is also very susceptible to freezing. The binder, for example cement, is very dry and of relatively small volume and does not tend to become frozen in very cold conditions.
The mixing process is severely inhibited when the sand or water become frozen. As a result, the preparation of mortar becomes very difficult, if not impossible, in extremely cold weather.